Satellite Communication - Rapti Engineering College

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Council for Technical Education & Vocational Training
Rapti Engineering College
Ghorahi, Dang
Presentation on
Satellite Communication
Presented by
Shailendra Giri
WEL-COME TO PRESENTATION
Introduction:
In a satellite link, there are earth stations, which
send signals at a frequency band. When the
satellite is above the station, signal is received &
the satellite retransmits it after amplifying it at
another frequency.
Then signal can be received by ground
stations which are below the satellite.
Thus Geosynchronous satellites, it is
possible to establish communication link over
wide area as the satellite covers wider area
Important aspects are:
1.
2.
3.
4.
5.
Satellite should be as small and lightweights as
possible.
Should use minimum energy.
Should carry as many communication channels as
possible.
Since launchers & Satellite are expensive,
spacecraft should be capable of functioning without
maintenance for many years.
Satellite should be designed with as much flexibility
as possible to cope with the changes in
communication technology.
Geosynchronous satellites provide the following
advantages:
Satellite appears stationary relative to earth. Therefore
tracking of antennas is not necessary
No need to switch from one satellite to other and
therefore no break in transmission.
One satellite is capable of covering about 40% of the
earth and hence large numbers of earth stations are
linear-connectable.
Just 3 satellites are enough to cover the entire globe.
Geosynchronous satellite has the following
demerits:
Regions of the earth above 80 degree latitude cannot be
covered.
Since the distance is very large, the signal strength
becomes very
Because of large distance the signal suffers a delay of
540s in a two way communication
Up link frequency:
At this frequency the ground station
transmit signal to the satellite. Commonly
used bands are 6GHz & 14GHz.
Down link frequency:
The downlink frequency is lower
than up link frequency. Commaonly used
bands are 4GHz, 12GHz & 20 GHz.
Just 3 satellites are enough to cover the
entire globe. The regions of earth above
80 degree latitude cannot be covered.
Components of Satellites

Altitude & Orbit Control system

Telementry, Tracking and Command

Power System

Communication Subsystems

Antenna Subsystem
Thank You
For Your Time
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